The role of endogenous cationic proteins (ECPs) in glomerulonephritis will be examined. ECPs are isolated from platelets and characterized. ECPs being positively charged are predicted to bind to glomerular polyanion within the glomerular basement membrane and mesangium, effectively neutralizing the charge barrier to circulating (anionic) macromolecules. The effect of ECPs on glomerular permeability to macromolecules and immune complexes will be evaluated using in vivo and in vitro techniques. Some ECPs are known to have important biological effects (induce chemotaxis, increase vascular permeability, are mitogenic, etc.). Experiments are designed to study the phlogenic properties of ECPs in the kidney following injection into the renal artery. Extrapolation of animal studies to human glomerulonephritis will be attempted by demonstration of ECPs in renal biopsy tissue by immunofluorescence techniques.